This invention relates to an apparatus for treating gas and more particularly to an apparatus for treating gas by placing it in intimate contact with a liquid. More specifically, the present invention is directed to an apparatus for treating air with a liquid, such as water, said apparatus being of the type generally used in air conditioning and air washing systems. In these systems an air stream is passed through a housing into direct contact with water by discharging the water into the air stream as it moves through the apparatus.
At one time, apparatus for treating air with water as generally used in industrial applications was severely restricted in operating velocities due to the configuration of the eliminators employed in the apparatus. Eliminators are normally used to remove entrained water particles from the air stream before the air stream is discharged from the apparatus. These eliminators usually consisted of a plurality of stationary blades having a general saw-tooth cross-section which define zigzag paths through the eliminators. The path configuration is intended to result in the impingement of the liquid particles on the blades where the liquid is collected and drained. Generally, these eliminators are effective up to a predetermined velocity at which point the liquid droplets in the air stream tend to pass through the eliminator construction. One of the reasons for this passage of liquid through the eliminator construction is the splattering or impinging of the water droplets on the blade surfaces in such a manner that the liquid passes back into the air stream and continues with the air stream out of the apparatus.
In order to ameliorate the situation, the tendency was to extend the zigzag path by adding more stages so that eventually all the water droplets were removed. Unfortunately, when this expedient was utilized, the pressure drop through the unit was increased, thereby requiring larger fans to be used to pump the air. Naturally, the acceptable pressure drop through the eliminator and the consequent fan size have an upper limit which is easily reached and as a result this approach was not truly a solution but was only an expedient.
U.S. Pat. No. 3,444,670 of Ernest C. Hungate discloses an improved eliminator structure, in which an impingement device including vertically extending wall portions angularly disposed with respect to the gas stream is positioned upstream of a plurality of substantially vertical wall members defining zigzag paths. The trailing ends of the wall portions of the impingement device have tab portions which define vertically extending channels which collect the liquid hitting the wall portions and allow it to drain to the bottom of the housing. The vertical wall members are covered with a resilient foam material, such as urethane, which contains a large number of small openings and a plurality of passages. The fine liquid particles which reach the vertical wall members penetrate the surface of the foam and drain freely while sheltered to a great extent from the air stream.
Although there are improvements in performance of the apparatus of U.S. Pat. No. 3,444,670, two sets of wall members are required, thereby increasing manufacturing time and costs. In addition, the foam material increases the manufacturing costs, as does the operation of coating the wall members. Furthermore, provisions are required to protect the foam from the gas stream, such as clips attached to the leading edges of the vertical wall members.
U.S. Pat. No. 3,527,030 of Ernest C. Hungate discloses a further improvement in the eliminator structure, in that impingement surfaces are incorporated in the leading ends of the substantially vertical wall members defining zigzag paths. The impingement surfaces include substantially vertically extending grooves having an offset portion and a fluid stream reversal portion so that the direction of the gas flow and the direction of flow of the liquid removed from the gas stream are substantially in confronting arrangement, thereby permitting the liquid to drain down the groove. However, this further improvement did not eliminate the need for coating portions of the wall members with foam and the provisions for protecting the foam from the gas stream.
Despite the fact that the devices disclosed in the patents mentioned above represent significant improvements in the art, they do not directly address the problems resulting from the fact that large quantities of the liquid in the gas stream flow along the walls of the housing and can, under certain conditions, overload the portions of the eliminator adjacent to the housing walls. When an overload occurs, significant amounts of liquid are not removed by the eliminator and are free to remain in the gas stream when it exits the housing. In addition, none of the known gas treatment apparatuses includes a simple structure for controlling the flow of gas.